Bellows as a part of a passage are sufficiently known from the prior art; the bellows are configured, for example, as folding bellows or also as corrugated bellows. Folding bellows are configured in the manner of a concertina and typically have an aluminum frame, which is U-shaped in cross-section, on their outside in the region of the gusset. These aluminum frames serve to increase the stiffness of the bellows.
Such frames, which likewise serve to increase the stiffness of the bellows, are also provided in a corrugated bellows in the region of the transition from one corrugation to the next corrugation.
The material for manufacturing the bellows comprises in detail at least one coat, but preferably a plurality of coats, of a reinforcement material, with a respective layer of an elastomer being provided on both sides of the reinforcement material. The coating of an elastomer can, for example, be a TPU, an EPDM or also a silicone. In particular the use of silicone has the great advantage of higher fire-resistance and UV-resistance.
It is now known that the thicker the coating is, the heavier the bellows become. This means that a bellows provided with a thick coating is very prone to sagging, which requires special measures to avoid the sagging. It is already known in this connection to provide a suspension device on the top side of the bellows from which the bellows is suspended. However, a certain thickness of the elastomer coating is necessary to ensure the leaktightness of the bellows material. The coating process itself also causes a certain thickness of the coating to be necessary.
It is furthermore known that bellows become dirty over time. Buses and rail vehicles are admittedly driven through washing systems, but it is in particular the case with folding bellows that the washing brushes do not extend in parallel with the folds, but rather transversely thereto. In this respect, the bellows is essentially not cleansed by a washing system of a conventional kind. Cleaning must rather be carried out by hand with the aid of a high-pressure cleaner as a rule. The use of high-pressure cleaners for cleaning bellows is in another respect also known in the aircraft passenger bellows of aircraft passenger bridges or aircraft passenger stairways. The use of high-pressure cleaners, however, has the disadvantage that the bellows wear faster from the use of high-pressure cleaners.
It has, however, been shown that surfaces having a lotus effect offer the dirt fewer weak points for adhesion, or dirt which collects detaches substantially more easily from the surface.
The surfaces of conventionally manufactured bellows materials are such that they are contaminated more or less strongly in dependence on the area of use and such that the dirt adheres strongly to the surface. This is due to the surface of the coating material or also to the reinforcement material if the latter presses through the coating.
In this connection, a bellows is known from DE 10 2009 023 823 B4, wherein the bellows material between the frame is laminated by a film. Such a film is easy to clean. It has, however, been found that the film does not remain permanently connected to the folding bellows material due to the movement of the bellows.
A so-called lacquer-coated bellows is known from DE 10 2010 006 939 A1, wherein a lacquer film is applied to the bellows material. The lacquer film is also easy to clean. This lacquer film also does not form any permanent connection to the coating material of the bellows.